This is my favorite for my iphone: from their website!
Lapua Ballistics is the ultimate 6DOF ballistics calculator for mobile devices. It’s the first mobile ballistics app utilizing the 6DOF calculation model, which makes it the most accurate ballistics app on the market. With Lapua Ballistics, you can calculate trajectories, range, bullet drop, turret adjustments and more to help take that perfect shot. Lapua Ballistics always offers the latest, Doppler proven Lapua cartridge and bullet data. It also includes the option to define custom bullets manually. At current, the Lapua Ballistics App is available in no less than eight languages: English, German, Finnish, Norwegian, Polish, French, Spanish and Afrikaans, for Android and iOS mobiles, free of charge.